I need to whip up a set of pad adapters for the RP18s and I have the adapters for the Kenwood KH-82s in progress, so I took pics...
Tools of the trade, except the missing steel ruler:
Step 1: Measure the outer diameter of the headphone front bezel, then subtract 2-3mm to account for slight variation when you actually cut out the ring or disc.
Step2: Measure the driver opening. This measurement will carry through the rest of the rings.
Step 3: Measure the OD of the pad mount. In my case I averaged 3 pads, the O2s, the Denons, and the K240s and called it 100mm.
Step 4: Measure the offset for the lip. This will set the OD of the inner spacer ring and give the necessary clearance for the pad to mount properly. This inner ring space is usually gapped to 1.5mm or 0.065" so that's the thickness sheet we'll need for the ring.
Step 5: After you have written down your dimensions you can determine the ODs and IDs of your rings and also determine if you will have enough area to get a good seal on the bezel with just an inner spacer ring or if you will need a third ring to mount to the headphone bezel. In my case the offset for the O2 pad was the largest at 15.35mm on each side and the total distance between the outside of the bezel and the driver opening was just over 25mm, so I will need the third ring to give a large mounting surface for the 2-sided tape.
Step 6: Convert your diameter into a radius and use the steel ruler to set your OLFA hole cutter.
Step 7: Start with your largest OD to determine your spacing requirements on your plastic sheet. Here I'm using clear polyester because it's softer and more flexible, but acrylic, ploycarbonate, polystyrene, or polyethylene sheet will work too. The black dot just locates the center for me.
Step 8: Layout all the ODs and IDs so you can see how the 2 or three rings will look. The first two are the thinner inner rings. The bottom four are on 2mm (0.085") thick sheet for the bezel mount and the pad mount rings.
Step 9: Start cutting! Always cut the OD first. You've been warned.
In the pics below I drilled out the center so I could chuck it my drill to sand the OD. Big mistake and major PITA to get the IDs cut out.
Step 10: Sand. The pic below is the pad mount, inner ring spacer, and YH100 adapter for one side of rythmndevil's YH100 to Koss R10 adapters plus the second inner ring for the other ear.
Step 11: Test fit the three rings and try to get the best alignment you can. Mark the ID of all three with a single, double, and triple hash mark for alignment guides when you are gluing them up. Use CA (superglue) to glue them together or you can use 3M Super 77 contact cement if you want or need to change the pad mount ring for larger variations in pad sizes.
Sorry, no pic of that yet.
Step 12: Use double sided tape to mount the pad adapter to you headphone bezel. If you want a really strong bond, use the bumper mounting tape from automotive parts warehouses, but wait until you know you absolutely will not have to get back into them for anytime to come as they will be nearly impossible to take off. It's not permanent, but damn close Skippy. I use a simple 3M double sided tape while tweaking.
That's it. That's all it takes to becoming a pad rolling junkie without having to tear up your precious $35-$130 pad sets.